Chorioamnionitis, respiratory distress syndrome and bronchopulmonary dysplasia in extremely low birth weight infants

Objective: To determine if histologic chorioamnionitis (HC) in the presence of respiratory distress syndrome (RDS) augments adverse pulmonary outcomes in extremely low birth weight (ELBW) infants. Study Design: We retrospectively identified 184 ELBW infants who were born at and admitted to the neonatal intensive care units between June 2005 and June 2009. Results: The mean gestational age of the cases was 27 +/- 2 weeks, and the mean birth weight was 791 +/- 147 g. A total of 88% (161/184) of patients developed bronchopulmonary dysplasia (BPD). HC was observed in 71 of 238 infants (39%). When infants were divided on the basis of the presence or absence of HC and RDS, the incidence of moderate or severe BPD and duration of oxygen requirement were greater in the HC+RDS+ group than in the HC+RDS+ or HC+RDS- groups. The combination of prenatal (HC) and postnatal (RDS) injuries increased significantly the risk for BPD. In the multivariate analysis, the significant predictors of developing BPD were low gestational age (odds ratio (OR), 0.6; confidence interval (CI), 0.4 to 0.7) and exposure to both HC and RDS (OR, 4.7; CI, 1.1 to 20.2). Conclusion: The HC and RDS work synergistically to induce lung injury in ELBW infants. Chorioamnionitis may interact with RDS to further increase the risk of BPD, despite either HC or RDS could not show independent significant association with BPD. Journal of Perinatology (2011) 31, 166-170; doi:10.1038/jp.2010.113; published online 19 August 2010